Conventionally, radar apparatuses are known, which include an antenna for rotating on a horizontal plane and detect a target object around the radar apparatus by transmitting and receiving radio waves while rotating the antenna. The radar apparatus is capable of changing a pulse width of the transmission signal according to an instruction from a user etc. Further a pulse compression radar is capable of changing equivalent transmission power by changing a pulse width of a transmission signal. This type of radar apparatus is installed in a movable body (e.g., ship), a lighthouse, etc.
Further, depending on the installation circumstance of the radar apparatus etc., the transmission signal may be set to be transmitted only to a given angular range. This setting is used not to transmit rearward the transmission signal in a case where an obstacle (e.g., part of a ship) constantly exists rearward of the radar apparatus, etc.
Moreover, in Patent Document 1, an art of increasing the number of transmissions of a transmission signal per unit time for a given angular range is disclosed. Thus, it is possible to improve the resolution only for a required part while preventing an increase in data amount.